


Dirty Little Secret

by GemmaRose



Series: Kinktober 2019 [16]
Category: The Transformers (IDW Generation One)
Genre: Breast Worship, Casual Sex, Cervix Penetration, Consensual Kink, Degradation, Dom/sub Undertones, Dry Orgasm, F/M, False Spike (Transformers), Multiple Orgasms, Oral Sex, Plot What Plot/Porn Without Plot, Secret Relationship, Size Difference, Sparring, Teasing, Temperature Play, Verbal Humiliation, gagging
Language: English
Status: Completed
Published: 2019-10-30
Updated: 2019-10-30
Packaged: 2021-01-03 04:02:38
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,190
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21173105
Author URL: https://archiveofourown.org/users/GemmaRose/pseuds/GemmaRose
Summary: Thunderclash has a reputation, amongst the citizens of Fort Tel'Adre. It's not a bad reputation by any measure, he's known to be kind and helpful, a protector of those who need protecting, an upholder of true justice and just all around good guy. It is a lot to live up to, though, and sometimes he just needs to take a mega-cycle to get away from it all, decompress where few mechs know who he is, and those that do don't care.The best of these mega-cycles are the ones where he runs into a certain Unicron-forged flamethrower whose tactlessness and attitude is, well, refreshing in a very Unicronian way.





	Dirty Little Secret

Thunderclash wouldn’t say he _enjoyed_ life on Unicron more than he’d enjoyed life on Cybertron, at least what he could remember of it, but it was certainly more interesting. Most mega-cycles he worked in Fort Tel’Adre, helping mechs with whatever was needed, doing his best to keep their city a bright spot against the darkness of this corrupted and corruptive planet. Whenever he had time to himself though, the rare day when he had no social calls to make or duties to attend to, he headed outside of the city’s walls. His few friends who knew where he vanished to were the ones he trusted to understand, to _get_ that as much as he liked his reputation as a good mech and would work to uphold it, sometimes he just needed a break to be less than the perfect idol so many perceived him to be.

He headed out across the silica sands, angling east towards the forest and lake which lay on the other side of the mountains. The plains and mountains had their own beauty to them as well, their own draw, but of late he’d found himself seeking the luminous woods and calm, cool oil on what he internally deemed his mega-cycles off. The sands faded gradually into oil-soaked filings, and Thunderclash took a moment to recalibrate his optics, letting them adjust to the greater levels of light in this area. A quick visual scan assured him that the self-proclaimed orgy boat was nowhere in the vicinity, and he relaxed a little as he began his stroll along the shore. The tessons who lived in the lake were weak enough he wasn’t worried, and the few mechs who chose to live in the area were cordial, aside from the boat crew.

A cycle or so of walking though, and Thunderclash began to grow restless. The lake was unusually calm, its surface glassy save the iridescent sheen, and even living primarily in Fort Tel’Adre, away from the dangers of this world, Thunderclash knew that unusual on Unicron almost certainly meant dangerous. He backed away from the shore, and as he reached the treeline he spotted a pair of optics rising from the oil. He didn’t look away until there were at least two trees between him and the lake, and exhaled heavily as he turned to wander the forest instead. Here he had to be slightly more careful, the minis were no threat on their own but their sheer numbers could overwhelm a mech half again his size, the tentacle beasts were slag if they got the drop on you, corrupted plant-mechs who didn’t take no for an answer could usually put up a fair fight, and he knew of at least two bugformer hives which actively attempted to get mechs hooked on fragging them in order to bring them home to the Queen. Rumours varied on why, but few who accepted that invitation ever returned.

Aside from all that though, the forest was really quite nice, all the luminous foliage making it easily the best lit place aside from inside a settlement. The plains were close, but grasses weren’t half as bright, and the fact that it was all underlighting confused the optic. Thunderclash ducked under a branch, and found himself looking into a glade absolutely packed with the corruptive flora so common on Unicron. Flowers that resembled a valve and node, trees that bore breasts complete with nozzles and a tantalizing energon-pink glow, vines sturdy enough at the end to use as a false spike. No elode, thankfully, and no immediately evident plant-mechs, but still not the sort of place the Great Thunderclash would be caught dead visiting.

Thunderclash smiled and stepped further into the glade. He knew how these places worked, he’d read the handful of studies on the effects of their various secretions. None of them were truly harmful, for the most part they simply increased a mech’s sensitivity and/or libido. This time... this time he thought he’d make use of the vines. Not every glade had ones large enough to satisfy him, but there were a few that looked promising here.

“Been a while since I saw you around.” a familiar voice said form behind him, and he spun to see just the femme he’d been hoping to run into.

“Been a while since I could get away.” he smiled, and Arson stepped into the glade, the air tangibly warming and growing heavy with ambient charge as she came closer, rousing the plants around them.

“Looking for something to replace me?” she teased, grabbing him by the hip plating and tugging. He went to his knees without complaint, sitting on his heels to bring himself closer to her height. 

“Never.” he promised, and her smirk was sharp enough to cleave a bot in two.

“Good. I’d hate to lose my favourite fragbuddy.” she grabbed him by the collar faring, and he let himself be pulled in roughly for a hard kiss, Arson’s fingers hot enough on his armour to be a warning. She could melt him without batting an optic, and he would have no defense. He leaned after her when she pulled away, and Arson laughed, bell-clear and cold in every way her frame wasn’t. “That desperate for me?” she teased, dancing back out of reach and reigning in the heat she put out constantly, coalescing it into a dim glow around her deceptively delicate-looking frame.

“Is it a crime to miss you?” he asked, rising to his pedes and wondering not for the first time if he should invest in some sort of weapon, or a shield. She would mock him for it, but that was hardly a problem.

“No, but it is kinda pathetic.” she said flippantly, and grinned as his engine missed a stroke. “Now were we going to fight, or are you going to _actually_ just roll over and try to win with your frame?”

Thunderclash shivered, and manually kicked his combat protocols into gear. “I’m ready to fight, but perhaps not here?”

“Good point.” Arson tossed him a smile, easy and genuine, a ray of sunshine on a world without sun or stars. It caught him off guard this time as thoroughly as it had every other. “It’d be a shame to burn this place down when I could get these vines to frag you stupid for me. Oh, sorry, _even stupider_.”

Thunderclash’s engine made a _very_ unhealthy noise, and he had to manually throttle down his fans before they could roar to life. Primus, how did she do that so effortlessly? Arson laughed again and caught him by the wrist, dragging him from the glade back towards the lake. The strange atmosphere from earlier was gone, along with the optics out in the oil, and Thunderclash steeled himself to spar with the vibrant mini who’d burnt herself a home in his spark with her callous words and searing touch. She dropped his hand, and sauntered another few mechanometers before turning around, the glow around her frame coalescing to flames around her hands with a snap as much tangible as it was audible.

“Alright, big guy.” she grinned, raising her burning fists. “Gimme your best.”

Thunderclash charged her with a roar, feinting a punch and following up with one that caught her as she dodged aside. Had she been any taller it would’ve thrown her down the beach, but as it was she just went skidding through the oily metal mulch, leaving a shallow furrow and short-lived flames in her wake.

“Nice.” Arson grinned as she rolled back to her pedes, shaking wet clumps from her external fuel tank and firing assembly. “But not good enough.” she charged him, and when he tried to sidestep she threw himself right where his pede would’ve come down. He lurched the other way, and as he flailed for balance she got her pedes back under her and launched herself up, ramming barrel-first into his middle and knocking him on his aft. He got an arm up to block her punch, but she just grabbed one of his fingers and yanked it back, planting one too-hot pede on his modesty panel as he cried out in pain and ramming the other into his chest. He went down with a hiss, clutching his possibly sprained finger to his chest, and Arson cackled.

“That was too easy, even for you!” she crowed, leaning forward to smirk at him. “Did a few little insults really get you running too hot to focus?” she shifted her weight to the pede on his modesty panel, which was rapidly warming into the territory of Uncomfortable. “Or is the Great and Mighty Thunderclash so desperate to be called a whiny little glitch that he’s willing to throw a fight?”

He couldn’t stop his fans from turning on that time, and when he turned his helm to look away Arson cackled. “Oh, this is _rich_.”

“Arson, please-”

“Please what, Clashy?” she jeered, and his spike pinged against the inside of his modesty panel, making him wince at the intense heat.

“Thunderclash?” a voice called, and Thunderclash went stone still. That wasn’t anyone who lived at the lake, and from the look on Arson’s face it wasn’t anyone she knew either, which meant a mech had followed him here from Fort Tel’Adre.

“Let’s get back to the glade.” he said hoarsely, and Arson’s expression turned from confusion to a wicked smile.

“You mean I shouldn’t invite them over?” she teased, and Thunderclash lurched upright. “He’s over he-” he got a hand over her mouth, one finger pressing down on her vocaliser to mute it, and scrambled to his pedes. It was only a few strides back into the forest, perhaps as many again before the lake was mostly hidden from view, and when he glanced back over his shoulder Thunderclash nearly swore. Wirey, the damn determined little medic had been trying to get him in her examination room for stellar cycles now. And she would _talk_ if she met Arson.

Thunderclash hurried as quietly as he could back into the woods in the vague direction of the glade, only removing his hand from Arson’s mouth and vocaliser when he was certain they were far enough off she wouldn’t try anything. “Are you really _that_ embarrassed of your kinks?” Arson snorted as he strode back into the glade and set her down, stretching leisurely.

“I have a reputation to maintain.” he muttered, and Arson rolled her optics.

“You city-bots are so weird. The only reputation that matters is who you fight, who you frag, and how well you do both.”

“And how would you rate me?” he asked. Arson shrugged.

“Decent fighter, _mostly_ decent frag. Speaking of which.” she gave him a sharp grin and jabbed a thumb over her shoulder at the tree laden with spike-vines. “On your back, Clashy.”

He settled on his back, pedes on either side of the tree, and Arson seated herself astride his hips before rapping on his modesty panel. His spike shot out against her ventral plating as soon as it was released, and Arson purred her engine as she ran a hand over it. “Clashy, one of these days I just might invest in finding a size changing blend.”

“Is that a compliment?” he teased, and Arson grinned over her shoulder at him.

“No. The only reason I’d do it is because I’m sick of doing all the work.” her modesty panel snapped open as she stood, planting a pede on Thunderclash’s thigh and reaching up to grasp the thickest of the spike vines. It twitched in her hold, its simple programming activating by heat and pressure, and stretched as she lowered herself, pulling it down with her. “Now, let’s see you _beg_.” she rubbed the tip of the vine against his valve, and the fluid it secreted made the already sensitive mesh feel like it was on fire, aching for stimulation.

“Please.” he choked out, using every byte of his willpower to not buck his hips up and take the vine into himself. Arson was seated astride his thigh now, but still within easy reach of his very sensitive array, and wonderful as her unnatural heat felt he didn’t want to know what literal flames felt like on his spike.

“Did you get even dumber since last time?” Arson scoffed, slender fingers dipping into the seam on his inner thigh and brushing too-hot over the sensitive wires there, making his frame spasm and his entire array _throb_. “I didn’t say ask, I said _beg_.” she caught a wire in her fingers and tugged, making him cry out as the signals scrambled in his neural net, pleasure so intense it was nearly pain mixed with a burning so sweet it was easy to confuse with pleasure.

“Please.” he blurted again, fingers digging into the ground beneath him and thighs trembling with the effort of holding still. “Please, please, stick that vine in my valve. I need it, I need-” he broke off in a wail as Arson rammed the immediate tip of it into his valve, leaving him writhing on the forest floor as he was unexpectedly stretched. And it just kept coming, too. Normally the vines stopped once the imitation spike was inside, but this one kept going, kept pushing deeper and deeper until it hit the back of his valve, lighting up his ceiling node and nearly pushing him to overload.

“That’s my big ol’ lump of shareware.” Arson purred, and Thunderclash realized she was using her flames to make the vine press deeper into him. “Now, open your tank port. I know you can.” Thunderclash shivered, fans kicking higher as he realized what she was planning. He found the override code, and moaned as it activated, the vine pressing through a port never before breached until almost the entire length of the imitation spike was settled inside his gestation tank. “Sit up.” Arson ordered, and Thunderclash pushed himself mostly upright, spreading his legs so as not to crush the vine jammed up his valve. He could sense the weight of it in his tank, and it made him feel off-balance.

“Now, remind me why I should frag you?” Arson grinned, moving to kneel over his spike, the wet heat of her valve so _close_ to his aching spike.

“Because-” the vine moved in his valve, its pseudo-organic texture rubbing against his inner walls as the imitation spike shifted in his port, and all threads in his processor promptly derailed.

“Becaaauuuse, you’re a piece of shareware?” Arson grinned, lowering herself so the tip of his spike barely brushed her valve, lubricant so hot it was nearly boiling dripping onto the sensor-laden metal. “Because you abducted me, that one time?”

“That was-” Thunderclash moaned, fingers curling nearly to fists in the ground below him. “A mistake.”

“One of _many_.” Arson agreed, and his fans whined. “Or perhaps, you want me to frag you because you’re just that desperate?” she reached out and dipped her searing hot fingers between the slats of his abdominal vent, stealing all the air from his systems. “Great and Mighty Thunderclash, beloved by all. Can’t get laid because his paint job looks like it was done by those weird little triplets.”

Thunderclash could only moan as Arson lowered herself another micrometer, the heat of her so close it was unbearable, so close that the denial was like torture. “Because- you want to.” he gritted out, and without missing a beat Arson reached up and caught the next largest vine, which had come slinking down towards the source of heat and charge.

“If I wanted a good frag, I could use this.” she brought the tip of the vine to her mouth and closed her lips around it, sucking down its sensitising, borderline-aphrodisiac pre-fluid with a moan.

“But then-” Thunderclash shuddered, his arms trembling as the vine in his valve began to find something like a rhythm, the non-spike portion of it compressing and thickening to pull the spike-like tip almost out of his port before decompressing to ram it back in. “Then you-”

“Yes?” Arson grinned, the vine in her hand oozing pale pinkish fluid over her fingers, and Thunderclash’s whole frame trembled. He knew what she wanted him to say, knew that when she repeated it he might overload on the spot just from hearing her say it without a hint of irony, but still the part of him which cared so much about his reputation balked at the idea of forcing the words out of his vocaliser.

“Then you wouldn’t get to- to use me like the shareware I am.”

“Oh, it looks like even morons _can_ be trained.” Arson grinned, leaning forward and holding the vine in her hand to his lips. “Even a cheap piece like you should have no problem taking care of this, right?”

The vine thrust into his mouth as soon as he opened his lips to answer, and it muffled his moan as Arson dropped herself onto his spike, so hot it burned and tight enough he wanted nothing more than to thrust up into her valve forever. His hips jerked up, spike sinking deep enough to brush her ceiling node, and the sound Arson made sent him over the edge into the most intense overload he’d had in a stellar cycle, at least. Arson grabbed tight to his vent slats as her own overload hit, fingers burning hot enough to scorch, and Thunderclash moaned loudly into the spike tentacle pressing even deeper into his mouth, forcing itself down his intake until he was getting pop-ups on his HUD warning of foreign objects and imminent tank purges.

He dismissed and cancelled them, gagging on the vine as it fragged his face in earnest, and Arson moved one of her her hands higher on his frame for support as she began to ride his spike, what little of it fit in her tight, burning hot valve. “Frag, you- useless- stupid-” she grunted, ramming herself down onto his spike with more power than most would’ve guessed a frame as slight as hers could generate. “Do I have to do _everything_, you glitched lump of shareware?”

Thunderclash’s optics could barely focus past the vine enthusiastically fragging his mouth, especially as his charge surged dangerously close to overload again, but he could make out the warm colours of Arson’s frame and the pink-tinged grey in the middle, her modest chest exposed and the hand not scorching a mark into his chestplate fondling her breasts. He shifted his weight to one trembling arm and lifted the other towards her, letting Arson grab him by the wrist and direct his hand where she wanted it.

“Nice to see you’re not _completely_ processor-dead.” she huffed, her other hand sliding down to toy with her own node. The moan that left her vocaliser was utterly musical, her lubricant searing down the length of his spike and setting Thunderclash’s processor spinning even faster, and he muffled his moan in the spike vine fragging his intake as his charge spiked. “That’s it, that’s it.” Arson panted as he groped her breasts, so small he could fit them both in his one hand but so very perfect on her frame. He couldn’t imagine that a larger pair would flatter her frame well at all, they would disrupt the sleek lines of her armour and get in the way of her transformation.

“Come on, Clashy.” she grunted, grinding down hard on his spike, working the tip against her ceiling node. “Overload for me, you stupid- useless- shareware.” she brought herself down roughly on his spike between each word, subglyphs sharp enough with disdain to cut, and Thunderclash overloaded hard, his transfluid spurting right back out just like last time, heated by having been cycled through Arson’s valve and accompanied by her stinging hot lubricant as she overloaded as well. He tweaked one of her lovely little nozzles, and Arson’s whole frame arched, both her hands flying to his forearm for balance as he did it to her other breast. Back and forth he twisted and pinched them, processor swimming as she kept riding his spike, fresh spurts of lubricant bathing his spike in unbearable heat that he wanted more of, wanted to bury his whole spike in and _worship_.

“Right there, right-” Arson moaned loudly, overloading again, and Thunderclash was abruptly catapulted into another overload of his own as the spike vine in his intake slammed deeper than before and released its aphrodisiac seed. He bucked up into her, the arm supporting him folding as every servo in his frame convulsed with the unexpected surge of charge, and Arson’s hands flew to his sensitive vent slats, gripping there as she rode his spike even harder, chasing her overload.

“Come on, come-” her vocaliser cracked around a moan, static crackling from her mouth to match the charge that sparked in her field. “Stupid- useless- shareware.” she panted, fragging herself on his spike as her fingers scraped over his vent slats, dragging lines of flaming bliss across the sensor-laden metal. He moaned as her words sent fresh charge shooting through his frame, the sound unmuffled as the spike vine withdrew, and Arson abruptly moved one of her hands to grip his spike itself, making him gasp and buck up into the heat, the pressure. It hurt in the best way, his sensornet blending burning pain with the most sublime pleasure, and the clench of his valve calipers finally triggered the spike vine sunk so deep in him to spill its overload into his gestation tank.

The shock of aphrodisiac being pumped directly into his internal forge threw him into another overload, and Arson followed without even a nano-klik of delay, a vision of ecstasy as she writhed atop his spike, silvered thighs trembling and helm thrown back, chest thrust forward into his hand. And his overload just. Kept. Going. The spike vine wasn’t stopping, pumping more and more of its high-charge aphrodisiac directly into his tank, battering the port and scrambling his processor with pure, undiluted lust. His hand fell from Arson’s chest to claw at the ground, vocalizer near totally static as he writhed in helpless pleasure. It was too much, too much, and when the vine pressed somehow _deeper_ his vocaliser shorted out entirely, leaving him silent on the forest floor.

His tank felt tight against the underside of his armour, too full to fit within the default configuration of his frame but not full enough to buckle his armour outward, and his valve kept clenching down on the frantically pumping vine, nodes lighting up as it pulsed with more and more fluid to fill him further. “Ar- Arson.” he forced out as his vocaliser rebooted, vision swimming too badly to find her outline among the colours of the glade, all the different lights blurring together in a big smear that only made everything even more intense.

Her reply was sharp, cutting, and his processor was too scrambled to make out the words but her tone pushed him to overload yet again, transfluid tanks straining to push anything else out. Finally the vine in his valve fell limp and still, warm fluid spraying his thighs and making charge dance along his seams, and Thunderclash shuddered as the pressure in his gestation tank began to drop. Arson sat herself on one of his thighs, and he let out a crackling, broken moan when her hand landed on his hip, so close but so far from his array.

“Such a needy lump of shareware.” she sighed, sliding her palm flat over his pelvic armour towards his array. “Can you even beg right now, or is your pitiful little processor too full of charge for that?”

Thunderclash could only whimper, optics shuttering as he dug his helm into the ground below it, arching up into Arson’s touch. His spike twitched, aching from the inside out as his tanks pulsed empty, and Arson chuckled. “Guess you really are a _cheap_ piece of shareware. Not even built well enough to take a marathon frag from a spike vine.” he whimpered, charge shivering through his frame, and Arson’s hand paused _just_ shy of his anterior node, so close it tingled from the heat rolling off her fingers. “Good thing I don’t care about your valve.” she lifted her hand completely, rising off of his thigh, and Thunderclash let out a strangled sound which was almost a No, almost her name.

“What?” she laughed, her heat shifting up his side until he heard and felt her drop to her knees next to his helm. He onlined his optics, and the disappointed sound that left his vocaliser at the sight of her flame-decorated chestplate was completely involuntary. “You’re just shareware, you said it yourself.” she grinned, tapping him on the nose. “Shareware’s excess charge isn’t my problem.” she stood, giving him a wonderful view of her fluid streaked legs and sealed modesty panel, and Thunderclash shuttered his optics with a moan as she walked away. Frag, and he was still so _charged_.

He couldn’t even hate her for it.

**Author's Note:**

> This Arson is, in fact, the same OC who shows up in my other au [Hot Splicing, Rebellions, and Multiverse Shenanigans](https://archiveofourown.org/series/1524353), just forged on Unicron this time instead of in the functionist universe. She was carried by the Megatron in the MegaDriftRod piece, and sired by that Rodimus, before Drift arrived on Unicron and the three of them became a polycule.


End file.
